'88 Suzuki 150hp overheating

Just replaced waterpump impellar since was overheating at idle on muffs on one head and still is, other seems cool enough. Pulled thermostat on hot head but after testing on stove it sems to be opening and closing properly. Suggestions?

Also managed to break off two of the 6MM bolts holding the thermostat housing. So far have not been able to get a 7MM tap so planning on going up to 8MM. Going to try an easy out first but not real hopeful therefore figuring on using a 1/4" bit to open for the 8MM tap. Suggestions?

Appreciate your help.

Bill

Re: '88 Suzuki 150hp overheating

Suggestions ...... on the overheating part .... any warnigns on the tach?, you sure enough oil getting to the cylinder etc? .... and last but not least ... seeing that your bolt snapped off, seems like you have quite a bit of corrosion there so it wouldn't surprize me if there is a blockage somewhere that prevent water from getting to that specific cylinder .... which means stripping and cleaning ....

Re: '88 Suzuki 150hp overheating

deejaycee_2000 said:

Suggestions ...... on the overheating part .... any warnigns on the tach?, you sure enough oil getting to the cylinder etc? .... and last but not least ... seeing that your bolt snapped off, seems like you have quite a bit of corrosion there so it wouldn't surprize me if there is a blockage somewhere that prevent water from getting to that specific cylinder .... which means stripping and cleaning ....

Click to expand...

What would the tach show? Haven't run in awhile so using premix in addition to oil injection, so assume it's getting enough oil. What's procedure for stripping and cleaning?

thanks

Re: '88 Suzuki 150hp overheating

If there is overheating the tach would show you warning lights and buzzers .... if you running 50:1 premix that should be fine ... stripping and cleaning ... mmm not a fun job, although these days you get a solution you can clean off salt corrosion to a certain extent, it happens from not flushing your motor after running in salt water, if you really want strip to clean all the water channels you will need to take off the powerhead and take the whole thing apart and it can be very trickey if you're not a macanic .... if you snapped of 2 bolts allready .... I can just imagine how many bolt will snap off trying to take the powerhead apart ..... I would suggest finding out about a solution you can run through to try and clear the cooling system, I don't know much about that as I always flush if been in salt water, I do fresh water mostly, so do a search in the forums and see what you can come up with ...... good luck

Re: '88 Suzuki 150hp overheating

Warning light did come on on one side which prompted me to check with a laser gun and when it showed about 175/180 degrees plus an extremely hot pee stream I turned off. Other head was holding at about 115/120, therefore no warning lght.

At first I thought maybe I didn't line up the water tube correctly when I put lower unit back on but assume I would have overheat on both heads, not just one? Do you agree? After I did the new impellar and restarted at idle the pee stream was coming but not with a lot of force, then about a minute later it started coming with a lot of force for about 30 seconds, then reverted back to
the lesser (but steady) flow. Sounds like first, before the caustic solution, a back flush would be in order and if so should I flush through the thermostat hole or somewhere else and would it be necessary to drop the lower unit again?

I agree 100% with your feelings about the problems I would have in removing the power head. I only found one post about using a caustic solution and that guy used a hull cleaner. Maybe somebody will have some specific thoughts on what I should use and again where is the best place to put it in? Again, would the open thermostat hole be the best place or do I need to pull something else to gain better acess? Also do you think I need to pull the other thermostat in order to do the other head, or leave well enough alone? Also since I probably will have to give it 2 or 3 doses and will want to run freshwater through in between, assume I can run engine for short time without thermostat housing?

I just recently aquired this engine where all six are showing 90 PSI compression so I really don't know its' history but outwardly (with cowel removed) the engine
looks very clean. Any thoughts on how to flush when boat stays in salt water when there is no fixture on the engine for that purpose? Make any sense to *** it up each time, attach muffs and run, and if so would it be ok to do at full tilt or would it have to be lowered back into the salt water?

thanks again.

Re: '88 Suzuki 150hp overheating

Can anybody answer questions I raised in last post?

thanks

Re: '88 Suzuki 150hp overheating

For the bolts the best thing is to redrill for 6mm if done correctly you can save the old holes

The next best thing would be and M6 heli -coil set to repiar it to its orginal size

The really best thing is to use learn to use a Oxy-Ace Torch or you going to be breaking a lot more bolts


Tommays

Re: '88 Suzuki 150hp overheating

thanks tommays

Any thoughts on the other questions I had relative to solving my overheat problem?

1 .assuming I would have overheat on both heads if I had re-installed lower gear case incorrectly?

2. should I have let the temp build beyond that 180 degree (pee stream was real hot too), hoping it might drop down, before turning it off? My warning beeper never did go off in the 3/5 minutes it ran before I turned it off.

3. Know of any effective flushing solution that I can get and should I do it through thermostat hole or somewhere else? Do i need to drop the lower unit again to do a flush? Can I run the engine without causing damage for a short time, leaving the thermostat hole open, if it makes sense? Should I blow compressed air in through thermostat hole or somewhere else, hoping to blow out any obstruction?

4. Any other suggestions on how I can clean out the cooling passages short of removing the whole power head?

thanks
Bill

Re: '88 Suzuki 150hp overheating

I drill out a LOT of broken hardware but dont know much about your cooling system


BUT give it some time and you will get and expert answere they may all be at work right now


Tommays

Re: '88 Suzuki 150hp overheating

Thanks again Tommays. Hopefully I will get answers re my cooling system problems/questions.

Bill

Re: '88 Suzuki 150hp overheating

Well Bill, I read your post after seening your response to mine....here's my take and just so you know, I'm not a mechanic. However, I am a chemist and may be able to give you some insight as to what's goin on in there.

As Tommays had mentioned in a previuos post....if you have already broken off bolts holding th T-stats....thats a sure some of corrosion problems. I'm not sure if Japan has ever heard of anti-sieze but it would prevent most of these bolt breaking problems if used. I guess they don't feel you should ever have to take the engine apart.

After following several mechanics suggestions that responded to my post, I came to the conclusion that the hole in the C-head were probably blocked. After removing the heads,,, it was confirmed. I was also told that there was no flushinf of the system that would remove the scale blockage and they are correct. The scales of calcium that develop in the waterways is rock hard. The heads on mine engine are being sandblasted to remove the scales...

After my current experience with my engine overheating, I would recomend a slow approach to removng the C-heads if you think there is a blockage. If takes a week to remove all the bolts, thats time well spent. Do yourself a favor and do a search on removing the head bolts and read.

Good Luck

Re: '88 Suzuki 150hp overheating

Thanks Sunpacman. Couple more questions.

Would you have seen the blockages by just removing the cylinder head cover and if so, would you have been able to clean out sufficiently, avoiding removal of the head itself? Since assume the c- head cover must be removed to properly clean the head, is it best to first remove cover before removing the head from engine?

Did you use heat on the c-head bolts and if so what type? Did you follow the manual directions of lossening each bolt half turn at a time, in a crisscross pattern to prevent warpage, or was that impossible?

Is the sandblasting suppose to clean out all the waterways or will you still have substantial cleaning to do yourself? What type of shop is doing the sandblasting...a machine shop, or?

Did you pull off any other major components besides the c-head(s) and if so which ones? Any special tools required?

What were your overheat problems that prompted the c-head removal?

Bill

Re: '88 Suzuki 150hp overheating

Can any one please answer the questions I raised in my two posts: 11 of 18 and 16 of 18?

thanks
Bill

Re: '88 Suzuki 150hp overheating

This is correction to question I posted yesterday.

Can any one please answer the questions I raised in my two posts: #11 and #16?

Trying to determine the steps, and in what order, I should follow to solve my overheat problem. In my mind, removing the entire power head is a last resort. In fact, as I have questioned, did I turn off the engine too quickly when c-head temp according to laser gun got up to about 175/180 degrees (had run about 3/5 minutes) and the pee stream was too hot to feel? Perhaps the thermostat was just opening (have since verified that it works) and I should have waited another minute or so to see if temp on that one side was going to come back down?

thanks

Re: '88 Suzuki 150hp overheating

Can any one please answer the questions I raised in my two posts: #11 and #16?

Trying to determine the steps, and in what order, I should follow to solve my overheat problem. In my mind, removing the entire power head is a last resort. In fact, as I have questioned, did I turn off the engine too quickly when c-head temp according to laser gun got up to about 175/180 degrees (had run about 3/5 minutes) and the pee stream was too hot to feel? Perhaps the thermostat was just opening (have since verified that it works) and I should have waited another minute or so to see if temp on that one side was going to come back down?

thanks

Re: '88 Suzuki 150hp overheating

wjob said:

Thanks again Tommays. Hopefully I will get answers re my cooling system problems/questions.

Bill

Click to expand...

Re: '88 Suzuki 150hp overheating

Drilled and tapped fresh holes for thermostat cover. Then ran engine both with and without the thermostat on the one side (didn't remove other thermostat) to compare temperatures. With thermostat out that side started to build temp until it got up to around 180* using a laser heat gun, other side was down around 115*, then suddenly each side started to reverse itself. 115* side climbed to 195* and side without thermostat dropped to about 115/120* with cool pee stream.

Next, put thermostat back in which I verfied was opening correctly and that sides temp gradually rose over a five minute period to about 195*, including scalding hot pee stream, when I turned it off. Other side stayed at about 120*. My temp alarm never went off and all temp. measurements are based on the heat gun.

Will appreciate suggestions on my next moves.

thanks
Bill

Re: '88 Suzuki 150hp overheating

wjob said:

Just replaced waterpump impellar since was overheating at idle on muffs on one head and still is, other seems cool enough. Pulled thermostat on hot head but after testing on stove it sems to be opening and closing properly. Suggestions?

Also managed to break off two of the 6MM bolts holding the thermostat housing. So far have not been able to get a 7MM tap so planning on going up to 8MM. Going to try an easy out first but not real hopeful therefore figuring on using a 1/4" bit to open for the 8MM tap. Suggestions?

Appreciate your help.

Bill

Click to expand...

Re: '88 Suzuki 150hp overheating

dont know about you but muffs don't work on my dt150 its an 88 also ,alarm kept beeping, put it in the water after changing pump and impeller and it worked fine when i got home i threw out those muffs they're made for newer engines, i suggest going to a quiet launch and try it on your trailer, good luck.